Provenance implications of reworked palynomorphs in Mesozoic successions of the Porcupine and North Porcupine basins, offshore Ireland

Reworked Late Carboniferous palynomorphs are recorded from mudrocks within Upper Jurassic and Lower Cretaceous sandstone-prone horizons from five wells (26/28-A1, 26/28-AIZ, 35/19-1, 35/8-1 and 35/8-2) in the Porcupine and North Porcupine Basin area, offshore western Ireland. Reworked palynomorphs are recognized by their anomalous biostratigraphic age; differences in colour and preservation are less significant. The reworked palynomorphs are remarkably well preserved and are thermally relatively immature in comparison with in situ onshore palynomorphs of a similar age. This indicates that the source of the reworked palynomorphs was not the onshore Upper Carboniferous successions of the Irish mainland. They were probably derived, along with the associated sand, from the immediate basin margin to the east, as this is the only area where there is suitably aged material with an appropriate thermal history. Reworking of rift flank Late Carboniferous material was thus an important factor in the provenance of Mesozoic sandstone horizons throughout the Porcupine and North Porcupine basins and surrounding areas. The study demonstrates that the investigation of reworked palynomorphs can be an important aspect of provenance studies in general.